.box {
  width: 100px;
  height: 300px;
  background-color: red;
}
.box > div {
  width: 500px;
  height: 500px;
  background-color: teal;
  margin: 10px;
}
.box > div > div {
  width: 300px;
  height: 300px;
  background-color: #80003c;
  margin: 10px;
}
.box > div > div > div {
  width: 200px;
  height: 200px;
  background-color: #048000;
  margin: 10px;
}
